In additon, the LookUp column could not be delegated within SP list, so above AddColumnsfunction would cause a Delegation issue on your side. In order to get rid of this Delegation issue, please take a try with the following workaround:

Set the OnVisible property of the first screen of your app to following:

In additon, the LookUp column could not be delegated within SP list, so above AddColumnsfunction would cause a Delegation issue on your side. In order to get rid of this Delegation issue, please take a try with the following workaround:

Set the OnVisible property of the first screen of your app to following: